Induction of functional xeno-free MSCs from human iPSCs via a neural crest cell lineage.

Mesenchymal stem/stromal cells (MSCs) are adult multipotent stem cells. Here, we induced MSCs from human induced pluripotent stem cells (iPSCs) via a neural crest cell (NCC) lineage under xeno-free conditions and evaluated their in vivo functions. We modified a previous MSC induction method to work under xeno-free conditions. Bovine serum albumin-containing NCC induction medium and fetal bovine serum-containing MSC induction medium were replaced with xeno-free medium. Through our optimized method, iPSCs differentiated into MSCs with high efficiency. To evaluate their in vivo activities, we transplanted the xeno-free-induced MSCs (XF-iMSCs) into mouse models for bone and skeletal muscle regeneration and confirmed their regenerative potency. These XF-iMSCs mainly promoted the regeneration of surrounding host cells, suggesting that they secrete soluble factors into affected regions. We also found that the peroxidasin and IGF2 secreted by the XF-iMSCs partially contributed to myotube differentiation. These results suggest that XF-iMSCs are important for future applications in regenerative medicine.

Generation of a human SOX10 knock-in reporter iPSC line for visualization of neural crest cell differentiation.

SOX10 (SRY-box transcription factor 10) is not only a definitive molecular marker of neural crest cells (NCCs) but also an essential transcription factor for the differentiation of NCCs in vertebrate embryogenesis. Here, we report the establishment of a human SOX10 knock-in reporter iPSC line (SOX10-tdT) by CRISPR/Cas9-mediated homologous recombination, in which the expression of SOX10 can be monitored as tdTomato fluorescence. This iPSC line can provide a useful tool to model the differentiation process of human NCCs in vitro.

Generation of human GAPDH knock-in reporter iPSC lines for stable expression of tdTomato in pluripotent and differentiated culture conditions.

Human induced pluripotent stem cells (iPSCs) can differentiate into multiple cell types and are utilized for research on human development and regenerative medicine. Here, we report the establishment of human GAPDH knock-in reporter iPSC lines (GAPDH-tdT1 and 2), via CRISPR/Cas9-mediated homologous recombination, that stably express tdTomato as a constitutive cell label in both iPSCs and their differentiated derivatives. These cell lines will provide useful tools to trace cell locations and fates in 2D cultures and 3D organoids and will facilitate in vivo experiments.

Viral RNA detection by RIG-I-like receptors.

In higher vertebrates, recognition of the non-self signature of invading viruses by genome-encoded pattern recognition receptors initiates antiviral innate immunity. Retinoic acid-inducible gene I (RIG-I)-like receptors (RLRs) detect viral RNA as a non-self pattern in the cytoplasm and activate downstream signaling. Detection of viral RNA also activates stress responses resulting in stress granule-like aggregates, which facilitate RLR-mediated antiviral immunity. Among the three RLR family members RIG-I and melanoma differentiation-associated gene 5 (MDA5) recognize distinct viral RNA species with differential molecular machinery and activate signaling through mitochondrial antiviral signaling (MAVS, also known as IPS-1/VISA/Cardif), which leads to the expression of cytokines including type I and III interferons (IFNs) to restrict viral propagation. In this review, we summarize recent knowledge regarding RNA recognition and signal transduction by RLRs and MAVS/IPS-1.

Certain carotenoids enhance the intracellular glutathione level in a murine cultured macrophage cell line by inducing glutamate-cysteine-ligase.

SCOPE: Glutathione (GSH) increases in RAW264 murine macrophage cells exposed to ß-carotene or ß-cryptoxanthin, however, the underlying mechanism has not been clarified. In the present study, we investigated the expression of glutamate-cysteine-ligase (GCL), the rate-limiting enzyme in GSH synthesis, in these cells. METHODS AND RESULTS: Both the protein and mRNA expression of GCL increased in a ß-carotene concentration-dependent manner. Buthionine sulfoximine, a GCL inhibitor, abolished the ß-carotene-induced GSH increase without affecting the ß-carotene-induced GCL protein expression. Both cycloheximide, a translation inhibitor, and actinomycin D, a transcription inhibitor, completely suppressed the ß-carotene-induced GCL protein expression and the concomitant GSH increase. Actinomycin D inhibited the ß-carotene-induced Gcl mRNA expression as well. Similarly to ß-carotene, ß-cryptoxanthin upregulated the GCL protein expression, but lutein did not. The c-Jun N-terminal kinase (JNK) inhibitor, SP600125, suppressed the ß-carotene-induced GSH increase, whereas a p38 mitogen-activated protein kinase inhibitor or an extracellular signal-regulated kinase 1/2 inhibitor did not. The JNK inhibitor also suppressed the ß-carotene-induced GCL protein expression, and consistently ß-carotene induced JNK phosphorylation. CONCLUSION: These findings revealed that certain carotenoids induce the Gcl mRNA expression in RAW264 cells and subsequently the GCL protein expression, which concomitantly enhances the intracellular GSH level, in a JNK pathway-related manner.